Radiation shield for spark plugs



Jan. 19, 1954 a. o. JOHNSON, JR

RADIATION SHIELD FOR SPARK PLUGS Filed Feb. 8. 1951 INVENTOR V GUY 0.JCHNSON, JR. BY

flf/ar/Itj Patented Jan. 19, 1954 2,666,423 RADIATION SHIELD FOR, SPARKPLUGS Guy D. Johnson,

the United States of A the Secretary of the Ar Jr., Red Bank, N. J.,assignor to merica as represented by Application February 8, 1951,Serial No. 210,044

1 Claim.

(Granted under Title 35, U. S. Code (1952),

' sec. 266) The invention described herein may be manufactured and usedby or for the Government for governmental purposes, without the paymentof any royalty thereon.

This invention relates to radiation suppression shields for the highvoltage sparking systems of internal combustion engines and particularlyto shielding the spark plugs therefor.

The suppression of radiation is only one characteristic which suchshields must possess. The present invention has to do not only withprevention of radiation but is particularly directed to providing such ashield having maximum mechanical ruggedness coupled with greatlyfacilitated means for installing upon and removing from all types ofinternal combustion engines.

The invention also provides for tightly sealing the shielding systemagainst moisture, which not only prevents internal corrosion thereof butalso maintains the electrical system at its top eniciency.

The shield is composed of a top section and abase section. The topsection may have any suitable construction adapted to enclose the upperportion of the spark plug and has provision for the reception of the endof the high voltage sparking cable connected to the spark plugelectrode. Desirably provision should also be made for connection of thespark plug shield to the shielding system for the remaining elements ofthe engine sparking system.

The base section of the shield is of special construction and isgenerally cup shaped. The bottom wall thereof desirably is maderelatively thin and has an aperture therein for the reception of thethreaded nipple on the spark plug. The side wall of the base sectionextends upward to embrace the hexagonal wrench receiving portion of thespark plug and is provided with means to rotatably couple the basesection to the plug. The base section thus serves as a drive nut wheninstalling the spark plug. Desirably also the base section is providedwith screw threads for securing and sealing it to the top member of theshield.

It is an object of the invention to provide a spark plug shield offeringeffective radiation suppression together with superior structural characteristics.

A still further object of the invention is to provide a spark plugshield having means for installing which is adapted to the design ofconventional spark plugs especially with respect to their installationupon engines of conventional design.

Another object of the invention is to provide a spark plug shield havinga base portion interengaging with and acting as the driving means forthe spark plug when it is installed or removed.

A still further object of the invention is to provide a spark plugshield which can be installed and. serviced with conventional tools andstandardized equipment.

Other objects and features of the invention will more fully appear fromthe following description taken in connection with the accompanyingdrawings and will be particularly pointed out in the claims.

To provide a better understanding of the invention, a particularembodiment thereof will be described herein and illustrated by theaccompanying drawings in which:

Fig. 1 is the vertical cross sectional view of a preferred embodiment ofthe invention showing a spark plug in operative position within theshield;

Fig. 2 is a cross section on line 22 of Fig. 1;.

and

Fig. 3 is a cross section of line 3-3 of Fig. l.

A shield constructed under the principles of the invention is extremelycompact and for that reason may be applied to engines having limitedspace areas for the reception of spark plugs. The shield is composed oftwo main sections, a relatively short base section I and a top section2. The top section is secured to the base section in any desired mannersuch as by screw threaded means.

A convenient manner of tightly uniting the members I and 2 is to providescrew threads 3 upon the upper end of the base I. The screw threadsreceive a complementary threaded clamping member 4, having a flange 5arranged to overlie an outwardly extending flange 6 upon the lower endof the member 2.

To establish a tight connection between the members a compressibleelectrically conducting gasket 1 may be interposed between the top ofthe member I and the flange 6.

The member 2 as shown is substantially of hollow cylindrical form havingan internal diameter sufficient to receive the upper portion of thespark plug 8 and is provided with an internal insulating member 9secured to the inner surface thereof. The member 2 is made ofimperforate metal, as shown, to form a complete inclosure for the plug.

Any suitable means may be used to admit the spark plug cable ID to theinterior of the shield.

A desirable means is shown in the drawing wherein an aperture isprovided in the top wall of the member 2 and the insulating member 9through which the cable extends to be connected to the electrode II ofthe spark plug. The member 2 is also provided with an integrally formedsleeve l2 through which the cable extends and which is provided withscrew threads I3 for connection to a cable shielding system I4.

The base member I is constructed to impart to the whole shield a maximumof rigidity and durability coupled with a high degree of convenience forinstallation and servicing. With these ends in view the base isgenerally cup shaped having its side wall extending upward to embracethe lower portion of the spark plug and its hexagonal wrench receivingportion Ii. It will be noted that the member I closely embraces thespark plug and thus maybe made to present a small external diameter toenable it to be. readily received in. small areas such as the spark plugwells or other limited space provided therefor in conventional engines.

The upper portion of the base member i is made relatively heavy towithstand the stress imposed thereon by the. application of wrenchesduring installing :and removing operations. As shown herein the chamberwithin the base I has a cross sectional shape complementary to that ofthe hexagonal portion of the spark plug. The chamber may, however, haveany convenient contour which will effectively rotatably couple the basemember to the plug. The external face of the side wall of the basemember is provided with wrench receiving areas I6 of any form or theexternal face of the side wall may have a conventional hexagonalconformation. The upper portion of the base member is made cylindricaland has screw threads formed thereon for engagement with the thread uponthe clamping member 4-.

Thewrench re'ceiving'areas I6 are formed upon the relatively thick andrigid side wall of the base I thereby to withstand the excessivetorsional stress resulting from the application of installing wrencheswhile the bottom wall thereof is made relatively thin to be clampedbeneath theshoul der I1 of the plug.

The construction of the base member I may be modified by lengthening theside wall thereof and forming the wrench receiving areas thereon at apoint a substantial distance above the base of the plug. This modifiedstructure may be ading upon the cylinder block l9 of the engine and arebothrotated until the plug seats itself in opcrating position with theannular portion 20 of the "bottom" wall of the base member I clampedbetween the plug and the cylinder block of the engine. A conventionalgasket 2| may be insertedto morenompletely seal the plug to the engine.The top portion 2 is then secured in place by tightening the lockingmember 4.

It will be particularly noted that standard wrenches may be usedtoinstall, remove and service the plug and its shield. Servicing of. thesystem is readily" accomplished by removing. the locking member '4between the top section [and the base I whi'chpermits removal of the topsection 2 thus exposing substantiallythewholeiplug and shieldforinspecti'onand to perform. any required servicing operation.

I claim: 7

A cup shaped radiation'shield member'ior. a

spark plug having awrench receiving portion and a threads d attachingnipple "ending; in a shoulder, said member having a thin bottom wallwithja hole through which the nipple maybe inserted with the shoulderagainst said wall; and a side wall having an innersurf'acein thei'orm:'o'f'a Wrench to "be coupled to the wrench receiving portion oi thespark plug and a" corresponding outer surface in-the form of a wrenchreceiving means, and means on said side wall forattachihg a furthershielding member to enclosetiie'spark plug.

GUY D. JOHNSON"; Hi1;

References; "Cited? in.- the. file of this patent UNITED STATES PATENTSNumber Name Date 2,303,389 Rabezzana- -l. Dec; 11,. 1942 FOREIGN PATENTSNumber Country Date 1,475 Great Britain c Feb. "24,1900 227,408 GreatBritain d. Feb. 19. 1 925

